This study will be conducted to test the hypotheses that: 1) male and female speakers will experience continuous lengthening of their vocal tracts as a function of aging; 2) male and female speakers will have continuous expansions in their oral and pharyngeal lumina as a function of aging; 3) increases in human vocal tract length and/or dimensions with aging bring about consistent lowering of formant frequencies in male and female elderly speakers; and 4) male speakers will experience different patterns of vocal tract configuration changes and speech acoustic changes as a function of aging compared to female cohorts. Completion of the study will: 1) provide physicians, health science researchers and other clinicians with a new approach, which is non-invasive, cost-effective and does not expose subjects to radiation, to monitor human oral and pharyngeal lumina changes caused by normal aging, physiological abnormalities and/or structural damage; 2) provide health researchers and clinicians with new knowledge and normative data on the effects of aging on human oral/pharyngeal cavity changes; 3) provide health researchers and clinicians with a reliably established acoustic database and preliminary theoretical models that account for speakers' speech resonance changes related to senile changes in their oral and pharyngeal cavities; 4) provide a research model that will serve as a foundation for other studies involving elderly populations with various communication disorders (e.g., Parkinson's disease and Alzheimer's disease) who usually experience changes in their vocal tract configurations as a result of neurological damage; and 5) provide a research model that will serve as a foundation for other studies involving very young children and young adolescents for developmental delays and disorders.